Ireland-capped hooker Sheahan returned to the Munster side at the start of this season having missed most of the last campaign with a neck injury.
That injury cost him his place in the international set-up and a place in the Heineken Cup-winning squad but the Corkman, who will celebrate his 31st birthday in August, has started in 15 of Munster's 19 games this season.
Sheahan said: "Given where I was, even this time last year, struggling to get over injury, I am delighted I was in a position to be looking at extending my contract. Now that that's done I can concentrate on my rugby and look forward to what's ahead of us."
Sheahan made his debut for Munster in November 1996 against Western Samoa at Musgrave Park. Since then he has been capped 128 times by the province.
He made his senior Ireland debut as a replacement against the United States during the summer of 2000. He started his first international against Romania in June 2001 and scored the first of five Test tries against Samoa later that season.
Former Italy prop Pucciariello will celebrate his 32nd birthday in June and like Sheahan, he had little difficulty in making up his mind to stay. "For me, Munster is the best club of my career. I am very happy here and so is my wife and son.
"So, no, it wasn't difficult to decide to stay. Very easy in fact," he admitted.
"This is a great team. There are so many great players here - I am delighted to stay."
Pucciariello joined Munster from Bourgoin and made his first start in Munster colours in a pre-season friendly against Leicester Tigers in August 2005. He has played in 18 of Munster's 19 games this season, bringing his total number of appearances in the famous red jersey to 42.